In the past, there has been proposed a feed control device as disclosed in Document 1 (JP 2013-128337 A). The feed control device disclosed in Document 1 includes a controller configured to close a relay interposed in a main circuit and control a self leakage generator to cause pseudo electric leakage in the main circuit in response to reception of a state notification signal indicative of allowance of charging from an electric vehicle (electric automobile). In this conventional example, operation check of an electric leakage detector is conducted under such a pseudo electric leakage state. When the electric leakage detector operates properly to open the relay as a result of the operation check, the controller closes the relay again and starts charging the electric vehicle.
In contrast, when the electric leakage detector does operate properly as a result of the operation check, the controller causes self electric leakage by the self leakage generator after a lapse of a predetermined time period, thereby conducting the operation check of the electric leakage detector again. Accordingly, the conventional example disclosed in Document 1 conducts the operation check of the electric leakage detector again multiple times in order to reduce a possibility of false detection.
The electric leakage detector of the conventional example includes a zero sequence current transformer to measure unbalance between currents flowing through a pair of power supply paths constituting the main circuit. The electric leakage detector is configured to compare a secondary output of the zero sequence current transformer corresponding to a magnitude of the unbalance between currents, with a threshold value, and to determine that electric leakage has occurred when the secondary output exceeds the threshold value.
Additionally, the self leakage generator of the conventional example includes a series circuit of a fixed resistor and a semiconductor switch, and the series circuit is electrically connected to the pair of power supply paths. Accordingly, the self leakage generator makes a short circuit between the pair of power supply paths by connecting them via the fixed resistor by turning on the semiconductor switch, and thereby cause unbalance between currents flowing through the pair of power supply paths, which leads to a pseudo electric leakage state (hereinafter, referred to as self electric leakage).
In a case of the self electric leakage caused by the self leakage generator, a magnitude of such an unbalance current flowing through the main circuit depends on a difference between electric potentials of the pair of power supply paths, which can be determined by the power supply voltage (effective value) of the AC power supply connected to the main circuit and the resistance of the fixed resistor of the self leakage generator.
Note that, the AC power supply has different power supply voltages depending on countries or regions (destinations), and may be classified into two major systems: a 100 V system and a 200 V system. In view of this, the self leakage generator of the conventional example is required to include a fixed resistor which is selected from the fixed resistor with the resistance corresponding to the power supply voltage of the 100 V system and the fixed resistor with the resistance corresponding to the power supply voltage of the 200 V system in accordance with a desired destination.